Conversion of hydrocarbon oils



lllll C. H. ANGELL Filed Dec.

- CONVERSION OF HYDROCARBON OILS March 28, 1939.

INVENTOR CHARLES H. ANGELL Patented Mar. 28, 1939 PATENT OFFICE2,151,s2v CONVERSION or HYDROOARBON OILS Charles H. Angell, Chicago,Ill., assignor to Universal Oil Products Company, Chicago, 111., acorporation of Delaware Application December 30, 1935, Serial No. 56,592

4 Claims.

This inventionjparticularly refers to an improved process for theselective conversion of relatively low boiling and high boilinghydrocarbon oils accompanied by reduction of the 5 residual liquidconversion products to coke in a relatively high pressure coking chamberof the system and wherein the vaporous conversion products from thecoking chamber are subjected to continued conversion at substantialsuperatl mospheric pressure in a chamber separate from that wherein thecoke is produced.

It is well recognized that cracking operations wherein coke is producedto the exclusion of residual liquid give higher yields of desirable 15light liquid products, such as motor fuel, than those operated fortheproduction of residual liquid, due to the fact that a large proportionof the volatile components of the residual liquid, which are recoveredfrom the residue when it is 20 subjected to coking, are suitable forfurther conversion within the system to produce additional yields ofdesirable light distillate. However, when coking of the heavy liquidconversion products is accomplished at substantially atmospheric orrelatively low superatmospheric pressure the evolved vapors normallycontain an appreciable quantity of undesirable high boiling components,including entrained tars and pitch-like material which are unsuitablefor further conversion in 30 the heating coil of the system if theexcessive 35 range of motor fuel are ordinarily of inferior anti-knockvalue as compared to those resulting from the pyrolytic conversion ofthe same oil under similar conditions but without coking of the residualliquid products. This is particularly 40 true when selective conversionof relatively low boiling and high boiling oils is employed, since insuch operations the motor fuel resulting from relatively severeconversion of the relatively low boiling oils is normally of betteranti-knock value 45 than that resulting from lower temperatureconversion of the relatively high boiling oils, or of both oils incommingled state, regardless of whether or not coking is employed.

The present invention embodies a selective 50 cracking system, whereincoke is produced as the final product of the process, which avoids allof the disadvantages of ordinary coking operations.

One of the features of the invention resides in the use of relativelyhigh superatmospheric 55 pressure in the coking zone and in introducingthe vaporous products therefrom into a reaction chamber, also maintainedat a substantial superatmospheric pressure, wherein undesirable highboiling components of the vapors are separated from their lower boilingcomponents, the latter subjected to appreciable continue-d conversion inthis zone, whereby the anti-knock value of their motor fuel componentsis materially improved, while the high boiling materials. separated fromthe vaporous products in the reaction chamber are returned to the cokingchamber for further treatment and reduction to coke.

As another feature of the invention which is correlated with the featureabove outline, selected a low boiling fractions of the intermediateliquid conversion products of the process resulting from fractionationof the vaporous products from the reaction chamber are subjected toindependently controlled more severe conversion conditions than those towhich the higher boiling fractions of the intermediate liquid conversionproducts are subjected, and the resulting highly heated conversionproducts may be introduced into the reaction chamber or into the cokingchamber, or in part to both. When introduced into the coking chamherthey serve to supply additional heat to the materials undergoing cokingtherein and assist their reduction to coke. When supplied to thereaction chamber they commingle therein with the vaporous products fromthe coking chamber, supplying additional heat thereto, to assist theirfurther conversion in this zone.

In one embodiment, the invention comprises subjecting a hydrocarbon oilof relatively high boiling characteristics to cracking temperature andsuperatmospheric pressure in a heating coil, introducing the heatedproducts into an enlarged coking chamber also maintained at substantialsuperatmospheric pressure, wherein their high boiling components arereduced to coke, remov- 40 ing vaporous products from the coking chamberand introduc'mg the same into a reaction chamber also maintained atsubstantial superatmospheric pressure, wherein high boiling liquidproducts are separated therefrom and their lower boiling componentswhich remain vaporized in this zone are subjected to appreciable furtherconversion, removing said high boiling liquid products from the reactionchamber and returning the same to the coking chamber for furthertreatment, separately removing the vaporous conversion products from thereaction chamber after being subjected to said continued conversiontherein, subjecting the same to fractionation whereby their componentsboiling above the range of the desired final motor fuel product of theprocess are condensed as reflux condensate, subjecting fractionatedvapors of the desired end boiling point to condensation, recovering theresulting distillate, separating the reflux condensate formed by saidfractionation into selected relatively low boiling and high boilingfractions, returning the latter to said heating coil for furtherconversion, subjecting said selected low boiling fractions of the refluxcondensate to independently controlled more severe conversion conditionsof cracking temperature and superatmospheric pressure in a separateheating coil, introducing a regulated portion of the highly heatedproducts from said separate heating coil into the coking chamber tocommingle therein with the materials undergoing coking and assist thecoking operation, and introducing another regulated portion thereof intothe reaction chamber to commingle therein with the vaporous conversionproducts and assist their continued conversion in this zone.

Hydrocarbon oil charging stock for the process may be supplied,depending upon its characteristics, to either heating coil of thissystem, or, all or in part, to the fractionator as will be later morefully explained.

The accompanying diagrammatic drawing illustrates one specific form ofapparatus employing the features and advantages of the present inventionand in which the process of the invention may be accomplished.

Referring to the drawing, heating coil I is located within any suitablefurnace 2, whereby the oil supplied to the heating coil in a manner tobe later more fully described is subjected during its passagetherethrough to the desired conversion temperature, preferably at asubstantial superatmospheric pressure. The resulting hot conversionproducts are discharged in a continuous stream from the heating coilthrough line 3 and valve 4 into coking chamber 5.

Chamber 5 is also preferably maintained at a substantialsuperatmospheric pressure, which may be substantially the same orsomewhat lower than the pressure employed at the outlet from heatingcoil I, and the high boiling components of the heated products suppliedto this zone are reduced therein to substantially dry coke. The coke maybe allowed to accumulate within chamber 5, to be removed therefrom inanywell known manner (not shown), after the chamber is substantiallyfilled or after its operation has been completed for any other reason.When desired, a plurality of coking chambers may be employed, althoughonly one is illustrated in the drawing, in which case they may besimultaneously operated but preferably are alternately operated, cleanedand prepared for further operation, so that the duration of theoperating cycle of the process is independent of the capacity of thecoking zone. Chamber 5. is provided with a suitable drain line 6,controlled by valve I, and this line may also serve as, a means ofintroducing steam, water or any other suitable cooling material into thechamher after its operation has been completed and preferably after ithas been isolated from the rest of the system, in order to hastencooling and facilitate removal of the coke.

Vaporous products are withdrawn from the upper portion of the cokingchamber and directed through line 8 and valve 9 into reaction chamberII), which is also preferably operated at a substantial superatmosphericpressure. The pressure maintained in the reaction chamber is nor-.

mally somewhat lower than that employed in the coking chamber in orderthat the hot vaporous products from the coking chamber may betransferred to the reaction chamber without the use of a pump orcompressor. It is, however, entirely within the scope of the inventionto employ a suitable pump or compressor for this purpose, in

which case chamber I may, when desired, be operated at a substantiallyhigher pressure than that employed in the coking zone. Although notindicated in the drawing, the reaction chamber and the coking chamberare preferably well insulated in order to conserve heat and appreciablefurther conversion of the heated products supplied to the reactionchamber, and particularly their low boiling components which remainvaporized in this zone, is accomplished therein. The high boilingliquids formed in the reaction chamber or supplied thereto, includingany entrained or dissolved tars and pitch-like material in the vaporousproducts from the coking chamber and also including any residualconversion products and high boiling polymers supplied to this zone withthe heated products from the high temperature cracking coil of thesystem, in a manner to be later more fully described, momentarilycollect in the lower portion of the reaction chamber, from which theyare withdrawn through line II and valve I2 to pump I3, by means of whichthey are introduced through line I4 and valve I into the coking chamberfor further treatment and reduction to coke in this zone. The vaporousproducts which pass throughthe reaction chamber and undergo appreciablecontinued conversion in this zone are withdrawn, in the case hereillustrated, from the upper portion thereof and directed through line I6and valve I'I into fractionator I8.

It is, of course, entirely within the scope of the invention, althoughnot here illustrated, to supply the vaporous products from the cokingchamber to the upper instead of to the lower portion of the reactionchamber, in which case vaporous and liquid conversion products may beseparately withdrawn from the lower portion of this zone, the latterbeing returned, in the manner illustrated, to the coking chamber, whilethe vaporous products are supplied, by well known means (not shown), tothe fractionator.

The components of the vaporous conversion products supplied tofractionator I8 boiling above the range of the desired final motor fuelproduct of the process are condensed in this zone as reflux condensatewhich is separated by fractional condensation into selected relativelylow boiling and high boiling fractions, to be subjected to furtherconversion as will be later more fully described. Fractionated vapors ofthe desired end boiling point are withdrawn, together with uncondensablegas produced within the system, from the upper portion of fractionatorI8 and directed through line I9 and valve 20 to condensation and coolingin condenser 2I. The resulting distillate and gas pass through line 22and valve 23 to collection and separation in receiver 24. Gas may bereleased from the receiver through line 25 and valve 26.. The distillatecollected in receiver 24 may be withdrawn therefrom through line 21 andvalve 28 to storage or to any desired further treatment. When desired,regulated quantities of the distillate collected in receiver 24 may berecirculated, by well known means not illustrated in the drawing, to theupper portion of fractionator I8 to serve as a cooling and refluxingmedium in this zone for assisting fractionation of the vapors and tomaintain the desired outlet temperature'from the fractionator.

The high boiling fractions of the reflux condensate formed infractionator I8 are withdrawn from the lower portion of this zonethrough line 29 and valve 30 to pump 3|, by means of which they arereturned through line 32 and valve 33 to conversion, as previouslydescribed, in heating coil I.

The selected relatively low boiling fractions of the reflux condensateformed in fractionator l8 may be withdrawn from one or a plurality ofsuitable intermediate points in this zone, provision being made in thecase here illustrated for withdrawing the same from the fractionatorthrough line 34, wherefrom they are directed through valve 35 in thisline to pump 36. Pump 36 supplies the relatively low boiling refluxcondensate through line 31, valve'38 and line 39 to further conversionin heating coil 40, wherein they are subjected to independentlycontrolled conversion conditions more severe than those to which therelatively high boiling oils are subjected in heating coil l.

A furnace 4! of suitable form supplies the required heat to the oilpassing through heating coil 40 to subject it to the desired relativelyhigh conversion temperature, preferably at a substantialsuperatmospheric pressure. The resulting highly heated products aredischarged from heating coil 40 through line 42 and may thence pass, allor in part, through valve 43 in this line into reaction chamber Ill, orthey may be supplied, all or in part, through line 44 and valve 45 intocoking chamber 5. I

The invention specifically contemplates the introduction of regulatedportions of the highly heated products from heating coil 40 into boththe coking chamber and the reaction chamber. Any heated productssupplied from heating coil 40 to the coking chamber preferably aredirectly commingled with the heavy liquid conversion products undergoingcoking in this zone and serve to assist their reduction to coke. Anyhighly heated products from heating coil 40 supplied'to the reactionchamber commingled in this zone with the vaporous products from thecoking chamber, supplied thereto as previously described, serving tosupply additional heat thereto and assist'their continued conversion inthe reaction chamber.

Charging stock for the process, which may comprise'any desired type ofhydrocarbon oil, is supplied, in the case here illustrated, through line46 and Valve ll to pump 48, wherefrom it is fed through line 49 and maybe directed, all or in part, through line 50 and valve 5! intofractionator 18, through line 39 and valve 52, to conversion in heatingcoil 40, or through line 53,

valve 54 and line 32, to conversion in heating coil I. The mannerin'which the charging stock is supplied to the system will dependprimarily upon its characteristics. When it does not contain anyappreciable quantity of high boiling materials unsuitable for conversionin heating coil 5, or any appreciable quantity of materials within theboiling range of the overhead motor fuel product, which are of pooranti-knock value or would otherwise tend to contaminate the crackedmotor fuel product, the charging stock may be supplied, regardless ofits other characteristics, to the fractionator, and it is preferablysupplied to this zone when it comprises an oil of relatively wideboiling range, including materials corresponding in boiling range toboth the low boiling and high boiling fractions of the refluxcondensate. When the charging stock comprises an oil of relatively highboiling characteristics it may be supplied to heating coil I, and, onthe other hand, when it comprises an oil-of relatively low boilingcharacteristics it may be supplied to heating coil 40, or it may, ineither case, be supplied, all or in part, to fractionator i8.

The preferred range of operating conditions which may be employed toaccomplish the objects of the invention in an apparatus such asillustrated and above described may be approximately as follows:

The relatively heavy oil heating coil may utilize an outlet conversiontemperature ranging, for example, from 850 to 950 F., preferably with asuperatmospheric pressure at this point in the system of from 100 to 500pounds or more per square inch. The relatively light oil heating coilpreferably employs an outlet conversion temperature of from 900 to 1050F., or thereabouts, with a superatmospheric pressure measured at thispoint in the system of from 200 to 800 pounds, or more, per square inch.The coking chamber preferably employs a 'superatmospheric pressure ofthe order of 100 to 500 pounds, or thereabouts, per square inch, whichmay be substantially the same or somewhat lower than the pressureemployed in the communicating heating coil utilizing the lowestpressure. The reaction chamber may employ a superatmospheric pressure offrom 100 to .500 pounds, or thereabouts, per square inch, which, aspreviously mentioned, is preferably somewhat lower than the pressureemployed in the coking chamber, but may when desired be operated at asubstantially higher pressure than the coking chamber. The fractionatingstage of the system is preferably operated at a substantially lowerpressure than that employed in the reaction chamber, ranging for examplefrom 1-50 pounds, or thereabouts, per square inch down to substantiallyatmospheric pressure, although higher pressures up to substantially thesame as that employed in the reaction chamber may be utilized in thiszone when desired. The pressures employed in the condensing andcollecting portions of the system may be substantially equalized orsomewhat reduced relative to the pressure employed in the fractionator.

As a specific example of an operation of the process of the invention asit may be accomplished in an apparatus such as illustrated and abovedescribed, the charging stock, which comprises a California reducedcrude of about 24 A. P. I. gravity, is supplied to the heavy oilcracking coil, wherein it is subjected to a conversion temperature,measured at the outlet therefrom, of approximately 930 F. at asuperatmospheric pressure of approximately 350 pounds per square inch.The coking chamber to which the resulting heated products are suppliedis maintained at substantially the same pressure. Vaporous products fromthe coking chamber are supplied to the reaction chamber, which ismaintained at a superatmospheric pressure of about 340 pounds per squareinch, and liquid conversion products from this zone are returned,without additional heating, to the coking chamber. The fractionator towhich vaporous products from the reaction chamber are supplied ismaintained at a superatmospheric pressure of approximately 100 poundsper square inch, and the reflux condensate formed in this zone isseparated into components boiling above and below approximately 640 F.The high boiling fractions of the reflux condensate are returned to theheavy oil heating coil for conversion together with the charging stock.The low boiling fractions of the reflux condensate are subjected, in aseparate heating coil, to an outlet conversion temperature ofapproximately 950 F, at a superatmospheric pressure of about 400 poundsper square inch. Approximately 50% of the highly heated products fromthe light oil heating coil are introduced into the lower portion of thecoking chamber and the remaining 50%, or thereabouts, is introduced intothe reaction chamber. This operation will produce, per barrel ofcharging stock, approximately 62% of M10 F. end point motor fuel havingan octane number of approximately 70 by the motor meth d andapproximately 92 pounds of relatively low volatile petroleumcoke ofuniform quality and good structural strength, the remainder beingchargeable principally to uncondensable gas.

I claim as my invention:

1. A process for the conversion of hydrocarbon oils, which comprisessubjecting an oil of relatively high boiling characteristics toconversion conditions of cracking temperature and superatmosphericpressure in a heating zone, reducing the high boiling components of theresulting heated products to coke in a coking zone, introducing theheated vaporous products, including those resulting from the cokingoperation, into a separate reaction zone wherein they are subjected toappreciable continued conversion, withdrawing resultant high boilingliquid products from the reaction zone and returning the same, withoutadditional heating, to the coking zone, separately withdrawing vaporousconversion products from said reaction zone and subjecting the same tofractionation, subjecting fractionated vapors of the desired end boilingpoint to condensation, recovering the resulting distillate, returninghigh boiling fractions of reflux conden sate formed by saidfractionation to conversion in the heating zone, separately subjectingselected low boiling fractions of the reflux condensate to independentlycontrolled conversion conditions at higher cracking temperature in aseparate heating zone, and introducing regulated quantities of theresulting highly heated products into the reaction zone wherein theycommingle with the vaporous products from the coking zone and assisttheir further conversion.

2. A process for the conversion of hydrocarbon oils, which comprisessubjecting an oil of relatively high boiling characteristics toconversion conditions of cracking temperature and superatmosphericpressure in a heating zone, reducing the high boiling components of theresulting heated products tov coke in a coking zone, introducing theheated vaporous products, including those resulting from the cokingoperation, into a separate reaction zone wherein they are subjected toappreciable continued conversion, withdrawing resultant high boilingliquid products from the reaction zone and returning the same, without,

additional heating, to the coking zone, separately withdrawing vaporousconversion products from said reaction zone and subjecting the same tofractionation, subjecting fractionated vapors of the desired end boilingpoint to condensation, recovering the resulting distillate, returninghigh boiling fractions of reflux condensate formed by said fractionationto conversion in the heating zone, separately subjecting selected lowboiling fractions of the reflux condensate to independently controlledconversion conditions at higher cracking temperature in a separateheating zone, introducing regulated quantities of the resulting highlyheated products into the coking zone to commingle with the materialsundergoing coking therein and assist their reduction to coke, andintroducing another regulated portion of said highly heated productsinto the reaction zone to commingle therein with the vaporous productsfrom the coking zone and assist their further conversion,

3. In a process for the conversion of hydrocarbon oils, wherein an oilof relatively low boiling characteristics is subjected to crackingtemperature at superatmospheric pressure in a heating coil, theresulting heated products introduced into an enlarged reaction chamber,also maintained at a substantial superatmospheric pressure, whereinseparation of vaporous and liquid conversion products is accomplishedand the latter are subjected to appreciable continued conversion,vaporous and liquid conversion products separately withdrawn from thereaction chamber, the latter supplied, without additional heating, to acoking chamber, the vaporous products subjected to fractionation,fractionated vapors of the desired end boiling point subjected tocondensation and the resulting distillate recovered, the improvementwhich comprises returning selected low boiling fractions of refluxcondensate formed by said fractionation to said heating coil for furtherconversion, subjecting selected high boiling fractions of the refluxcondensate to independently controlled conversion conditions of crackingtemperature and superatmospherlc pressure in a separate heating coil,introducing the heated products from said separate heating coil into thecoking chamber, which is also maintained at a substantialsuperatmospheric pressure, withdrawing vaporous products from the cokingchamber, and introducing the same into the reaction chamber wherein theycommingle with the heated products from the first mentioned heating coiland are subjected to further con- ,version therewith.

